Present day video recorders are typically a combination of a video camera with a video tape recorder which are constructed so as to be portable. They are often called camcorders or video tape recorders (VTR). For the purposes of this application, they are referred to as video tape recorders. Present day portable video tape recorders use a video tape, usually contained within a cassette, as the recording medium. Recording is done in numerous formats, including analog BETA and VHS format, and the digital D1 format. A major disadvantage of video tape recorders is that video tape allows only linear access to a given point on the video tape. That is, if the tape has just finished recording, in order to access the beginning of a recorded session located at the beginning of the tape, the tape must be rewound.
The problem of linear access to video tape recordings is most obvious in the field of broadcast television news. Typically, a reporting crew goes to a news location with a video tape recorder and record an event. Upon completion of recording, the tape is rewound and then played back and transmitted, for example via satellite or microwave link, to a base station a studio facility. At the base station, the information then can be edited into a final news program.
Editing of moving pictures is commonly done digitally, using a non-linear computer-based editing system such as the Avid/1 Media Composer or the NewsCutter, both available from Avid Technology, Inc. of Tewksbury, Mass. Such a system typically digitizes, or, converts analog video signals into a digital, computer-readable format. Even if the video signal is from a digital video tape, linear access to information on the tape still presents the same problems. Tape recording, transmission and digitization are usually performed unless there is an actual live connection from the camera to the base station. Because of the amount of time required for rewinding, playback and transmission of recorded information from a video tape, there is typically a half hour delay between the completion of recording of an event and the time an edited version of the recorded event actually can be broadcast by the base station. This delay is a significant competitive problem in broadcast news where the time to air is very important as stations strive to produce “up to the minute” news coverage and broadcast.
Today, electronic still cameras exist which record a still image on magnetic medium, such as a floppy disk. Such a camera is described in U.S. Pat. No. 5,084,775, issued Jan. 28, 1991, and assigned to Sony Corporation. However, the camera described in that patent records still images only, not full motion video images. In addition, computer video capture systems exist, such as the NuVista video capture card available from RasterOps/Truevision, Inc. Such systems, however, have not been combined with a video camera reduced to the portable form to perform live digital capture directly from a camera without intervening tape.
Additionally, it has been recently suggested by some skilled in the field of moving picture recording that numerous problems with a non-linear digital moving picture recorder are insurmountable. In particular, it has been suggested that there is a large image quality trade-off with increased recording time capability. Additionally, it has been suggested that, using disk-based media, a little shake of the camera would cause a disk crash. Finally, it has been suggested that the disk media is substantially costlier than tape.
Additionally, while still picture editing is available in some digital still video cameras, such as described in U.S. Pat. No. 5,301,026, such editing is significantly simpler than a full-motion video editing system and thus, such a still camera is not capable of recording or editing moving pictures.
Additionally, it is known that in many television stations there are a variety of switching capabilities to allow multiple sources of information to be fed to a single output channel. These sources are generally locked to and synchronized with the output channel frequency. Switching is performed between vertical time intervals, i.e., between frames, using a vertical time interval switch (VTIS). However, in a camera, there are typically only two sources of output, either live images or playback from tape, which are designed to be preselected by a user during playback but do not incorporate a VTIS.